Many private and governmental organizations need to determine information regarding water flow over a geographic area of interest. Such information can be used for such purposes as determining setbacks for logging or other forestry operations, for use in determining water rights, habitat restoration, endangered species protection and the like. As an alternative to physically surveying a land area to plot stream/river flows, water flow can be estimated with a computer and a digitized topographical map. The U.S. Geological Service (“USGS”) has developed sets of digital elevation maps (“DEMs”) that cover the entire United States and can be used to estimate water flow. Most DEMs produced by the USGS have a spatial resolution of approximately 10×10 meters per pixel.
In addition to the USGS DEMS, many land areas have been mapped with higher resolution imaging systems. One such imaging system is a light detection and ranging system (“LiDAR”). With LiDAR, an aircraft is flown over a geographic region while a sweeping pattern of laser pulses are directed towards the ground. A detector detects reflections of the laser pulses. The roundtrip time of each reflected laser pulse is determined and used to assign the pulse a three-dimensional coordinate in order to create a three dimensional map of the underlying terrain. LiDAR DEM data can have a spatial resolution of 2×2 meters per pixel or finer.
While LiDAR or other high resolution DEM data can be used to produce better estimates of stream locations and drainage area sizes, such data is typically only available for small portions of a geographic region of interest. Therefore, there is need for a system that can integrate both lower resolution DEM data that covers a wider geographic area and higher resolution DEM data that provides more detail to determine stream vectors for a desired region of interest.